Not Applicable
1. Field of the Invention
This invention pertains generally to directed light fabrication processes, and more particularly to a device which provides uniform distribution of gas-carried material powder within a directed light fabrication system.
2. Description of the Background Art
Fabrication of three-dimensional solids by means of directed fabrication, such as directed light fabrication (DLF), involves injecting powders into a high energy density moving beam, such as a laser light beam. The powders are carried by a stream of gas, commonly argon, to the focal point of the laser beam wherein material fusing occurs. The gas provides a non-reactive carrier for the particles of the powder which are to be fused into a solid. In practice, though, the powder is often injected non-uniformly about the beam resulting in a build-up from the fused powder material that is also of non-uniform structure. The lack of uniformity is particularly noticeable when the laser beam changes direction, thereby causing a different orientation of powder injection relative to the beam motion. This lack of uniformity in the resultant solid due to the improperly distributed powders becomes even more pronounced when fabricating alloy solids from a combination of powders.
Achievement of a uniform finished structure therefore requires uniformity of powder injection. The multiple feed powder splitter in accordance with the present invention when used with a multiple-outlet nozzle for powder disbursement satisfies that need, as well as others, and overcomes deficiencies in current powder feed techniques.
The present invention distributes controlled powder flow rates to a series of output lines for dispersing powder which is entrained within a gas through nozzles for use within the directed light fabrication (DLF) process. The device comprises a number of modular splitter blocks which can be slidably interconnected. The slidable connection incorporates an integral flow control means that requires no moving parts. A combination of splitter blocks are interconnected to receive a flow of gas entrained powder from one or more hoppers. The flow of gas entrained powder is split into a number of tubular lines which are connected to feed the powder delivery nozzles.
An object of the invention is to split the flow of gas entrained powder into a series of output lines.
Another object of the invention is to control the relative amount of powder flowing into each powder flow splitter block without the need of moving parts employed within separate valve assemblies.
Another object of the invention is to provide a powder flow splitter system that allows configuration for various numbers of hoppers for supplying the powder material.
Another object of the invention is to provide for modular mechanical block interconnections which allow for rapid assembly, flow adjustment, and tear-down.
Another object of the invention is to provide an integrated flow control means for equalizing the flow of gas entrained powder.
Another object of the invention is to provide gas entrained powder flow passageways that do not restrict powder flow or unduly clog up.
Another object of the invention is to provide uniform distribution of incoming powder material among two outgoing passageways.
Another object of the invention is to provide a flow control means with minimal susceptibility to failure.
Further objects and advantages of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the invention without placing limitations thereon.